import turtle
points=[[0,100],[50,100],[100,100],[150,100]]
n = 0
def xq():
    turtle.clear()
    for i in range(len(points)):
        points[i]
        turtle.up()
        turtle.goto( points[i])
        turtle.down()
        turtle.dot(20,'red')
        points[i][1]-=10
    turtle.ontimer(xq,300)
turtle.tracer(False)
xq()
def sb(x,y):
    global n
    points[n][1]+=20
    n+=1
    if n >= len(points):
        n=0
turtle.onscreenclick(sb)
turtle.done()